A recruit can join the semi-secret 300 F club at the AmundsenScott South Pole Station

Chapter 18, Problem 87

(choose chapter or problem)

A recruit can join the semi-secret 300 F club at the AmundsenScott South Pole Station only when the outside temperature is below 70 C. On such a day, the recruit first basks in a hot sauna and then runs outside wearing only shoes. (This is, of course, extremely dangerous, but the rite is effectively a protest against the constant danger of the cold.) Assume that upon stepping out of the sauna, the recruits skin temperature is 102 F and the walls, ceiling, and floor of the sauna room have a temperature of 30 C. Estimate the recruits surface area, and take the skin emissivity to be 0.80. (a) What is the approximate net rate Pnet at which the recruit loses energy via thermal radiation exchanges with the room? Next, assume that when outdoors, half the recruits surface area exchanges thermal radiation with the sky at a temperature of 25 C and the other half exchanges thermal radiation with the snow and ground at a temperature of 80 C. What is the approximate net rate at which the recruit loses energy via thermal radiation exchanges with (b) the sky and (c) the snow and ground?